Nano-structured dielectric composite

Abstract

A multilayer dielectric structure is formed by vacuum depositing two-dimensional matrices of nanoparticles embedded in polymer dielectric layers that are thicker than the effective diameter of the nanoparticles, so as to produce a void-free, structured, three-dimensional lattice of nanoparticles in a polymeric dielectric material. As a result of the continuous, repeated, and controlled deposition process, each two-dimensional matrix of nanoparticles consists of a layer of uniformly distributed particles embedded in polymer and separated from adjacent matrix layers by continuous polymer dielectric layers, thus forming a precise three-dimensional nanoparticle matrix defined by the size and density of the nanoparticles in each matrix layer and by the thickness of the polymer layers between them. The resulting structured nanodielectric exhibits very high values of dielectric constant as well as high dielectric strength.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]This invention is related in general to nano-dielectric materials with plasmon-resonance electric-field effects tailored to enhance optical and dielectric properties. In particular, the invention pertains to a multilayer composite wherein three dimensional matrices of uniformly distributed nanoparticles are embedded between alternating continuous polymeric dielectric films.[0003]2. Description of the Related Art[0004]Electric energy storage devices, photovoltaics, displays, biosensors and a multitude of photonic devices could benefit greatly from advanced nano-dielectric materials that are tunable for particular electronic and optical applications. In general, nano-dielectric materials are evaluated for different performance characteristics of interest in various segments of the electromagnetic spectrum. For example, at low frequencies (1 Hz-1 MHz), the insulation properties of the material are important as they relate ...

AI Technical Summary

Benefits of technology

[0007]With regard to photonic applications, polymer nano-dielectric composites have been used for optical filters, photovoltaic cells, and various linear and non linear photonic devices. The literature describes composite materials that are either coated with conducting or semiconducting nanoparticles or contain nanoparticles in a host material, such as a liquid electrolyte or an insulating polymer dielectric. U.S. Pat. No. 7,486,400 (Saito) teaches a multilayer structure where conductive nanoparticle layers are stacked with alternating layers of dielectric SiO2 particles. Saito teaches that the behavior of such a multilayer structure can be controlled advantageously by alternating metal nanoparticles with dielectric nanoparticles and by selecting the size, horizontal density and vertical distance between them to increase the plasmon resonance effect (as measured by the absorbance of the material). Such structure, where particles are stacked to form a nanocomposite, can take advantage of the plasmon resonance effects in the optical part of the electromagnetic spectrum, but it is not applicable to lower frequency dielectric applications because materials that have gas inclusions in them are not appropriate for high strength dielectrics for capacitor, cables and transformer applications.

[0008]This invention is directed at producing nano-dielectric materials that have a precise multilayer structure where the size of the metal, semiconducting or insulating nanoparticles and the distance between them are accurately controlled to produce a multilayer three-dimensional structure that has tens to thousands of two dimensional nanoparticle layers accurately spaced in a void-free polymer medium. Unlike other composite systems that are loaded with conductive nanoparticles to the percolation limit, the distance from one nanoparticle layer of the invention to the next is accurately controlled by the leveling effect and the thickness of the polymer film deposited between them. As a result, the dielectric constant as well as the breakdown strength of the multilayer structure of the invention can be controlled and tailored to obtain optimal specifications for different energy-storage applications. In addition, the material of the invention exhibits tunable electro-optical properties available for a variety of electrical and optical applications for which nano-structured dielectrics have been heretofore unsuitable.

[0009]The invention is based on the concept of producing a nanocomposite dielectric material by alternating vacuum-deposited layers of nanoparticles and polymer dielectric layers of a specific thickness, so as to produce a structured, three-dimensional lattice of nanoparticles in a void-free polymeric dielectric material. As a result of the continuous and repeated de...

Problems solved by technology

At this stage of particle concentration, the dielectric constant of the composite becomes very high; however, the dissipation factor, the leakage current and the breakdown strength are compromised by the large clusters of agglomerated particles that short out segments of the dielectric.

This renders the high k material virtually unusable for high voltage dielectric applications.

However, higher voltage applications (e.g., 100V-1000V or higher) require that a large number of capacitors be connected in a se...

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